1. Field of the Invention
The invention generally relates to a recording apparatus such as an inkjet printer and a method for controlling the recording apparatus.
2. Description of the Related Art
In a typical inkjet recording apparatus, a recording head attached to a carriage ejects ink onto a recording medium placed on a platen to form an image (dots) on the recording medium while reciprocating the carriage in a main-scanning direction (i.e., a carriage traveling direction). The dots are repeatedly recorded on the recording medium while the recording medium is transferred in a sub-scanning direction (i.e., in a direction perpendicular to the carriage traveling direction) using a transfer roller, to thereby form a complete image on the recording medium. Note that the platen is a supporting member to support the recording medium while the ink is ejected onto the recording medium.
In the inkjet recording apparatus, a relative distance between the platen and the carriage may vary with a position of the carriage in the main-scanning direction due to an assembling error of the carriage, deterioration in sliding bearings of the carriage with aging, and the like.
When the relative distance between the platen and the carriage has varied with the position of the carriage in the main-scanning direction, the ink is attached to positions differing from desired ones (ideal positions) on the recording medium. Thus, it may be difficult to form the image with high resolution and stability.
Note that the above inconsistent distance between the platen and the carriage may also occur when the platen is shifted in the main-scanning direction. Similar to the carriage case, the platen may be shifted in the main-scanning direction due to an assembling error of the platen, aging of the platen, and the like. Further, if the platen is composed of plural plate members, the plate members maybe shifted with different angles relative to the main-scanning direction.
If the platen is shifted in the main-scanning direction, or the plate members of the platen are shifted with different angles relative to the main-scanning direction, the relative distance between the platen and the carriage may vary with the position of the carriage in the main-scanning direction.
As a result, even if the image is formed by reciprocating the carriage that is not tilted in the main-scanning direction, the ink may be attached to positions differing from desired ones (ideal positions) on the recording medium, which makes it difficult to form the image with high resolution and stability. That is, when the relative distance between the platen and the carriage varies with the position of the carriage in the main-scanning direction, the positions of ink droplets are shifted from the desired ones (ideal positions) on the recording medium. Thus, it may be difficult to form the image with high resolution and stability.
Japanese Patent Application Publication No. 2008-221729 (hereinafter called “Patent Document 1”), for example, discloses a technology for enabling registration adjustment corresponding to an unevenly curved recording medium in a main-scanning direction of a recording head while forming an image on the recording medium.
With this technology, a user configures a recording apparatus such that test patterns are recorded at two or more positions including projected portions and recessed portions of the unevenly curved recording medium while reciprocating the recording head in the scanning direction. The test patterns are recorded at the two or more positions set by the user on the recording medium in forward and backward traveling directions by making the recording time in the backward traveling direction different from the recording time in the forward traveling direction. The registration adjustment for recording an image on the unevenly curved recording medium in the backward traveling direction is made based on the recording time at which an optimal test pattern is recorded. Accordingly, the registration adjustment is appropriately made when the unevenly curved recording medium is used, and ink droplet misalignments on the recording medium obtained while recording in the reciprocating directions may be reduced.
In the technology disclosed in Patent Document 1, however, the user needs to set the positions on the recording medium at which the test patterns are to be recorded, which may create extra work for the user.
Moreover, the platen used in the technology disclosed in Patent Document 1 is made as a single unit, and hence, the platen formed of plural plate members connected in the scanning direction (carriage traveling direction) may be beyond the scope of the assumption. The ink droplet misalignments or the like due to the configuration of the platen formed of the connected plate members may not be controlled by the technology disclosed in Patent Document 1.